I like the grading options where you can see student responses on the left and leave comments on the right. I also like the student side of codio where the R environment truly maps the R studio interface. I've seen some other platforms add special functionality only for their platform and that can be confusing for students just learning to code.

I like how you have many options to structure your own questions. I also like the homepage for the daily tasks, it makes it very easy for students and teachers to keep track of assignments.

allows instructors to view students code